CSI sharing strategies for transmitter cooperation in wireless networks

Multiple-antenna "based" transmitter cooperation has been established as a promising tool toward avoiding, aligning, or shaping the interference resulting from aggressive spectral reuse. The price paid in the form of feedback and exchanging channel state information between cooperating devices in most existing methods is often underestimated, though. In reality, feedback and information overhead threatens the practicality and scalability of TX cooperation approaches in dense networks. Hereby we addresses a "Who needs to know what?" problem when it comes to CSI at cooperating transmitters. A comprehensive answer to this question remains beyond our reach and the scope of this article. Nevertheless, recent results in this area suggest that CSI overhead can be contained for even large networks provided the allocation of feedback to TXs is made non-uniform and to properly depend on the network\´s topology. This article provides a few hints toward solving the problem.